The known compositions which have found practical use as vaginal contraceptives typically incorporate an active ingredient which is spermicidal. In spite of their high spermicidal activity, however, vaginal contraceptives incorporating these materials are not as effective in preventing conception as would be desirable. In addition, there are some indications that these materials possess undesirable side-effects.
In accordance with the invention, there is provided a method for inhibiting conception in mammals in which the contraceptive effects are achieved, not by immobilizing spermatozoa, as in the case of spermidical contraceptives heretofore known, but by inhibiting sperm transport and/or by preventing certain sperm events necessary for fertilization. It has been found that certain compounds, hereinafter described, function as inhibitors of enzymes or other sperm components necessary for fertilization and have high contraceptive potency when used vaginally in mammals, in a concentration sufficient to prevent fertilization of ova by spermatozoa in the presence of the comounds.